Using this one currently, US$16.
You can find a more details review in Mobile01.
Amazon.com: SHIELD Apple 3G iPhone Shield Polycarbonate Slim Fit Case (White): Electronics (http://www.amazon.com/SHIELD-Apple-iPhone-Shield-Polycarbonate/dp/B001GI9U6U/ref=pd_sim_e_8)
http://ecx.images-amazon.com/images/I/41OBDnr1RwL._SS400_.jpg